The pipe under the pressure gauge should be bent. Most people don't know the reason!
The pipe under the pressure gauge should be bent. Many people see it every day, but in fact many people don't understand it. Many of these pipes are called pressure buffer pipes, which are used to connect the pressure gauge and the equipment or pipe measured by the pressure gauge. They are used to buffer the instantaneous impact of the measured medium on the spring pipe of the pressure gauge. They can well protect the mechanical structure of the digital display or the pressure sensor from damage and prolong the service life. There are many kinds of pipes, so it is necessary to select buffer pipes of different materials to measure different media, so as to ensure the accuracy of measurement and the normal operation of the measurement system. This elbow is called a condenser or siphon, According to the instruction 6.4 in the installation instruction of HK03 pressure / differential pressure measuring instrument pipeline connection Atlas (hg/t20581-2012 Edition), "for steam and other condensable hot gases, and when the medium temperature exceeds 60 ℃, the locally installed pressure gauge shall use the installation drawing with condensing pipe (or siphon) for the purpose of passivating the gas medium to prevent damage to the instrument. Of course, sh/t3104 instrument installation design specification also has similar instructions.
Those who have been in petrochemical plants should have seen that pressure gauges in some places are equipped with pressure buffer tubes, and some places are not equipped with them. In fact, they all have certain reasons. Most of the pressure gauges used are elastic spring tube pressure gauges. There are three types of pressure measurement. The measured pressure is relatively stable, and the upper range limit of the pressure gauge is about 4/3 of the measured maximum pressure. The measured pressure fluctuates greatly, and the upper range limit of the pressure gauge is about 3/2 times of the measured pressure. The measured pressure is in the occasion with large vibration, such as the outlet pressure of the pump. The upper range limit of the pressure gauge to be measured is about 1.7 times of the measured pressure. The meter bend has the effect of heat dissipation, but it eliminates the influence of high temperature on the pressure gauge not by heat dissipation, but by blocking convection. In case of heat dissipation, there should be one, two, three, four and other heat dissipation tubes with different turns according to the temperature. So the use of table bending is not heat dissipation! If you don't believe it, try a straight pipe with the same length as the circumference of the annular pipe - in the vertical straight pipe, the high-temperature medium will soon transfer heat to the pressure gauge through convection.
